We added a queen 3" memory foam topper to our mattress and did not cut the extra length off. That gives DH more length that he needs AND it makes the regular queen sheets fit fairly well. If we move, I just flip the topper back up and over so that when we put the slide in the regular mattress can move fully up against the closet like it should and the slide is totally closed. That topper added a lot of comfort to the bed. I would do that for your daughters bed too. If it is a bunk type bed, you can cut the topper down to the size you need. The denser the foam, the more comfort and the longer it will last. The x-tra topper could make a twin or full size sheet fit better. The bunks I have seen were twin size bunks, to twin size sheets.
Depends on how cold it gets where you are at. We wintered in central AL where propane was supplied for us. For example, we had 19 nights in Dec that it was at freezing or below. Over the course of the winter, we used approx 200 gallons of propane and supplemented with an electric heater. On the gulf coast of MS where it was somewhat warmer with fewer night that cold and only our cook stove using propane, we used about 20 gallons.